Risk assessment of groundwater with multi-source pollution by a long-term monitoring programme for a large mining area

Environmental problems caused by mineral exploitation have increased significantly, a situation that has serious effects on the surrounding groundwater quality, especially with respect to the descent of the groundwater table caused by deep mining and multi-source pollution produced by auxiliary projects. Therefore, the study of groundwater risk assessment from multi-source pollution and the development of a long-term monitoring programme to manage such problems are essential. A copper-molybdenum opencast mine was the target of this study. Based on an analysis of the hydrogeological conditions of the mining area, aquifer parameters were obtained through field drilling and pumping tests. A finite element subsurface flow (FEFLOW) system was utilized to construct a numerical model that can analyse and predict the migration of multi-source pollutants during groundwater pumping and drainage in the mining area. The migration of pollutants is controlled not only by natural groundwater flow, but it is also strongly influenced by water drainage during deep mining, an activity that causes the multi-source pollutants to migrate to the mining centre. Therefore, both influencing factors should be considered when assessing the risk of groundwater pollution by multi-source pollutants. A reasonable groundwater monitoring programme that considers the migration direction and the distance of the pollutants from the groundwater movement in a non-natural flow field under the influence of a groundwater funnel during deep mining is also necessary.